Adoptive transfer is a term coined by Medawar (1954, Proc. Royal Soc. 143:58-80) to study allograft rejection. The term adoptive immunotherapy denotes the transfer of immunocompetent cells for the treatment of cancer or infectious diseases (June, C. H., ed., 2001, In: Cancer Chemotherapy and Biotherapy: Principles and Practice, Lippincott Williams & Wilkins, Baltimore; Vonderheide et al., 2003, Immun. Research 27:1-15). Adoptive therapy can be considered as a strategy aimed at replacing, repairing, or enhancing the biological function of a damaged tissue or system by means of autologous or allogeneic cells. The first successful infusion of ex vivo expanded, HIV infected, polyclonal CD4 T cells that enabled a high degree of engraftment upon infusion, was performed using magnetic beads coated with anti-CD3 and anti-CD28 beads (CD3/28 coated beads) to ex vivo expand the HIV infected individuals T cells. Eight patients were administered 51 infusions of costimulated CD4 cells under this protocol with minimal adverse advents (Levine et al., 2002, Nature Med. 8:47-53).
HIV infection induces a pronounced expansion of HIV-specific CD8 T cells. These CD8 T cells release soluble factors (Walker et al., 1986, Science 234:1563-1566; Zhang et al., 2002, Science 298:995-1000; Cocchi et al., 1995, Science 270:1811-1815) that limit HIV replication as well as directly lyse HIV infected cells (Walker et al., 1987, Nature 328:345-348; Koup et al., 1994, J. Virol. 68:4650-4655). Depletion of CD8 T cells prior to SIV challenge leads to unchecked viral replication and a rapid death, indicating that CD8 T cell activity is necessary to make HIV a chronic disease (Schmitz et al. 1999, Science 283:857-860; Jin et al., 1999, J. Exp. Med. 189:991-998). Yet, CD8 T cells ultimately fail to control HIV infection. HIV-specific T cells have been shown to have highly reduced perforin expression (Zhang et al., 2003, Blood 101:226-235; Appay, et al., 2000, J. Exp. Med. 192:63-75), down-regulation of two key signaling receptors, CD3ζ and CD28 (Trimble et al., 2000, Blood 96:1021-1029), a skewed maturation pattern (Appay et al., 2002, Nature Med. 8, 379-385) and a high sensitivity to Fas induced apoptosis (Mueller et al., 2001, Immunity, 15:871-882). Thus, it is believed that optimal activation of HIV specific CD8 T cells will restore effector functions.
Anti-CD3 and anti-CD28 (CD3/28) coated beads were the first generation of artificial APCs (aAPC) that permitted expansion of HIV-infected CD4 T cells (Levine et al., 1996, Science 272:1939-1943). In addition to delivering the signals needed for T cell activation and growth, CD3/28 bead stimulation renders T cells resistant to R5 infection by down-regulating CCR5 and up-regulating the expression of its ligands, the β-chemokines RANTES, Macrophage Inflammatory Protein-1 alpha (MIP-1α) and MIP-1β (Riley et al., 1997, J. Immunol. 158:5545-5553 Carroll et al., 1997, Science 276:273-276). Several phase I and II trials have demonstrated that infusion of autologous CD4 T cells expanded using CD3/28 coated beads into R5-infected individuals is both safe and feasible (Carroll et al., 1997, Science 276:273-276; Levine et al., 2002, Nature Med. 8:47-53; Walker et al., 2000, Blood 96:467-474; Ranga et al., 1998, Proc. Natl. Acad. Sci. U.S.A. 95:1201-1206). More importantly, sustained increases in the total lymphocyte count, the CD4 to CD8 T cell ratio, the fraction of cytokine-secreting T cells, and the ability to respond to recall antigens were observed, suggesting that adoptive T cell immunotherapy can restore at least limited immune function back to HIV infected individuals (Levine et al., 2002, Nature Med. 8:47-53). Despite the success of these initial trials, several limitations were noted, including the difficulty of (1) expanding CD8 T cells, (2) adding additional costimulatory signals that may be required to expand certain subsets of T cells, (3) removing the beads before infusion and (4) generating antigen specific T cells with a high engraftment potential.
Others have used T cell expansion CD3/28 coated beads to introduce gene modified T cells to HIV infected patients. In these studies (Walker et al., 2000, Blood 96:467-474; Mitsuyasu et al., 2000, Blood 96:785-793; Deeks et al., 2002, Mol. Ther. 5:788-797), a chimeric molecule consisting of the extracellular domain of CD4 and the intracellular domain of the CD3 zeta chain (CD4ζ was introduced into CD4 T cells via retroviral transduction). CD4ζ-modified T cells were detected by DNA PCR in the peripheral blood of all patients following infusion, and mean levels of 1-3% of total peripheral blood mononuclear cells (PBMCs) were sustained at all post-infusion time points. In an extended follow-up, CD4ζ was detected in the blood of 17 of 18 patients one year following infusion. These levels of sustained engraftment are several orders of magnitude higher than what has been previously observed for human T cell infusions, perhaps because previous cell culture techniques may have induced susceptibility to apoptosis or replicative senescence (Rosenberg et al., 1990, N. Engl. J. Med. 323:570-578; Yee et al., 2002, Proc. Natl. Acad. Sci. U.S.A. 99:16168-16173; Brodie et al., 1999, Nature Med. 5:34-41; Riddell et al., 1996, Nature Med. 2:216-223; Riddell et al., 2000, Cancer Journal 6:S250-S258). These clinical results indicate that costimulated T cells propagated with bead-based aAPCs are safe and have the capacity for prolonged engraftment. However, due to the limited number of study subjects and length of time required to achieve a clinical endpoint in a HIV therapeutic trial, statistical significance of the clinical benefit of autologous CD4 T cell transfer to HIV infected individuals could not be measured.
While potentially effective in limiting immunodeficiency, polyclonal CD4 T cells are likely to have only a modest effect on the HIV specific response. Immunotherapy of human viral infection using adoptive transfer of antigen-specific CD8 T cells has been studied in the setting of CMV, EBV, and HIV infection. This approach has been evaluated using T cell clones with HLA-restricted antigenic specificity for CMV (Riddell et al., 1992, Science 257:238-241; Walter et al., 1995, N. Engl. J. Med. 333:1038-1044). CMV-specific CD8+ T cells isolated from MHC-identical bone marrow donors were expanded ex vivo and were administered to 14 allogeneic bone marrow transplant recipients. Recovery of CMV-specific CTL activity was seen in each case and adoptively transferred CTL persisted in vivo for up to 12 weeks. In a similar study, donor-derived EBV-specific CD8+ and CD4+ T cells, genetically marked with the neomycin resistance gene, were administered to 6 recipients of T cell-depleted allogeneic bone marrow allografts (Rooney et al., 1995, Lancet 345:9-13; Heslop et al., 1996, Nature Med. 2:551-555). Gene-marked CD4+ and CD8+ T cells responsive to in vivo or ex vivo challenge with EBV persisted at low frequencies in vivo for as long as 18 months after infusion. Infusion of CD8 T cells with a single specificity to HIV (Nef) (Koenig et al., 1995, Nature Med. 1:330-336) into one patient demonstrated CTL selection of viral variants indicating that infusion of HIV specific T cells against multiple targets may be necessary to control HIV replication. In all of these studies, the inability of the vast majority of these T cells to engraft has limited the study of the long-term effects of antigen specific CD8 T cell immunotherapy. A major challenge in the field is to expand CD8 T cells that will engraft and have potent effector functions on a long-term basis to more effectively fight chronic infections. However, despite the long-term need for sufficient numbers of therapeutic T cells, there are no methods available for expanding these cells.
HIV specific T cells are able to contain but not eradicate HIV. Studies that have removed CD8 T cells prior to, or during, HIV infection have demonstrated unchecked viral replication and a much faster progression to AIDS, indicating that CD8 T cells are important in controlling HIV (Schmitz et al. 1999, Science 283:857-860; Jin et al., 1999, J. Exp. Med. 189:991-998). However, HIV specific T cells in general, lack perforin expression (Gandhi et al., 2002, Annu. Rev. Med. 53:149-172) and other requisite effector functions to eliminate HIV from the host. Studies of long term non-progressors indicated that HIV specific T cells from these individuals are more likely to proliferate and contain perforin, demonstrating that CD8 T cells with enhanced effector functions may delay the progression to AIDS (Migueles et al., 2002, Nature Immunol. 3:1061-1068). Other investigators have demonstrated that two key signaling receptors, CD3ζ and CD28 are downregulated on HIV specific T cells (Trimble et al., 2000, Blood 96:1021-1029; Trimble et al., 1998, Blood 91:585-594; Trimble et al., 2000, J. Virol. 74:7320-7330), and that HIV-specific T cells are more sensitive to Fas induced apoptosis (Mueller et al., 2001, Immunity, 15:871-882). Appay et al. (2002, Nature Med. 8:379-385) examined the differences between HIV-, EBV-, and CMV-specific CD8 T cells based on CD27 and CD28 expression. Early differentiated T cells expressed both CD27 and CD28 and possessed poor effector functions but excellent proliferative abilities. Intermediate T cells were CD27 positive but CD28 negative, and these cells had limited proliferative and effector functions. The most differentiated T cells lack both CD27 and CD28, and these cells had little proliferative ability but enhanced effector functions. It was observed that most of the HIV-specific T cells had the intermediate phenotype. Therefore, the cells being “stuck” in this intermediate T cell phenotype that lack both proliferative capacity and effector functions may be the contributing factor to the ineffectiveness of HIV-specific T cells (Appay et al., 2002, Nature Med. 8, 379-385). Moreover, CD8 T cell function is highly dependent upon CD4 T cell function (Zajac et al., 1998, J. Exp. Med. 188:2205-2213; Shedlock et al., 2003, Science 300:337-339; Sun et al., 2003, Science 300:339-342) and since HIV targets CD4 T cells, the CD8 T cell defects observed in HIV infection could be the result of a lack of T cell help.
Thus, there exists a long-felt need to provide ways to stimulate T cells to combat various acute and chronic diseases and to promulgate sufficient numbers of therapeutic T cells for adoptive immunotherapy. The present invention meets this and other needs.